The present disclosure relates generally to reducing emissions from power plant exhaust and, more specifically, to systems and methods of reducing emissions by recovering carbon dioxide from an exhaust gas stream using a turboexpander and membrane.
Power generating processes that are based on combustion of carbon-containing fuel produce carbon dioxide as a byproduct. Typically, the carbon dioxide is one component of a mixture of gases that results from, or passes unchanged through, the combustion process. It may be desirable to capture or otherwise remove the carbon dioxide and other components of the gas mixture to prevent the release of the carbon dioxide and other components into the environment or to use the carbon dioxide for industrial purposes.
At least one known method for removing carbon dioxide from exhaust gas streams includes a carbon dioxide membrane that selectively removes carbon dioxide from exhaust gas streams. The process typically requires compression and cooling of the exhaust gas stream. However, energy consumption per unit of carbon dioxide in the process can be quite high, due in large part to the need to cool and compress the exhaust gas stream.